Heat exchanger with adjustable casing for varying recirculation



Dec. 15, 1953 1.. R. HUBER HEAT EXCHANGER WITH ADJUSTABLE CASING FOR VARYING 'RECIRCULATION Filed July 1, 1952 INVENTOR LUDW/G ff. HUBER ATTO R N EYJ of the annularly arranged radiator sections l, which shaft is journalled in suitable bearings l4 in an air directing baflle 6. The baflle 6 is formed as shown to direct the streams of air driven by the propellers 4 and 5 radially outward through the radiator sections I and the side openings ID of the casing. The shaft l3 may be driven by an electric motor or other means, not shown. The casing side walls above and below the side openings In limit the amount of the total air emerging from the units I that is expelled from. the casing 3, and act with the end walls of the casing as a guiding duct system to return a substantial part of such air to the suction zones outside the propellers 4 and 5, as shown by the arrows P3. This returned portion of the air is there mixed with the incoming fresh air drawn in through the central openings II and I2 in the direction of the arrows P1, and the mixed air is then forced radially outward through the sections I.

In order to make the output of the device adjustable without change in speed of operation of the propellers 4 and 5, the casing may be provided with cylindrical sleeves l and 8 which telescopically engage and may be slidably moved along the side walls of the casing. These sleeves l and 8 act as means for adjustably altering the area of the casing side openings II). By sliding the sleeves 1 and 8 toward each other so as to partially close the casing side openings I0, the proportion of air from the radiator units I which is returned for recirculation therethrough in the direction of the arrows P3 is increased with a corresponding reduction in the amount of air expelled from the unit between the adjacent edges of the sleeves through the openings II].

It has been determined by test that with a constant predetermined output of the propellers 4 and 5 and a given temperature difference between the fresh air and the hot water or other medium flowing through the radiator sections I, there is an adjusted position of the sleeves l and 8 in which a maximum amount of heat transfer to the air occurs. It has further been determined that this maximum amount of heat transfer subtantially exceeds the highest value of heat transfer obtainable for the same output of the propellers if the casing 3 is removed from the device, even if the radial depth of the radiator sections I is increased. In other words, this maximum amount of heat transfer represents a value which is obtainable without the return flow feature of the present invention only by increasing the output of the propellers 4 and 5, that is, by increasing the amount of energy required to operate the device.

Although the invention is not in any way dependent upon the accuracy of any theory herein expressed, it is believed that the increased operating efliciency of my improved heat exchanger arises from the following considerations. The amount of heat transferred is proportional to the product of the radiator surface area and the amount of air moved through the radiator in a given time interval. In order to move a given quantity of air through a radiator of given cross-section, a certain input air velocity is required. The air flow energy consumed in passing this air through the radiator rises With the third power of the air velocity. By moving the air at a relatively low velocity and recirculating part of this air through the radiator sections several times, the flow energy consumed in passing the air through the radiator sections is kept at a low value, while the amount of heat transferred between the radiator sections and the air is maintained at the desired value by recirculation.

The heat exchange device of the present invention has proved to be highly successful both as a heating device for heating the air in rooms and other enclosed spaces and particularly in vehicles, and as a cooling device for cooling gas or liquid and particularly as a cooler of water used in internal combustion engines. The device is useful as a heat exchanger for other purposes as well.

I claim:

1. A heat exchanger comprising an annular radiator surrounding a central space, a casing surrounding and spaced from the annular radiator and having at least one central opening adjacent the central space of the annular radiator and at least one side opening adjacent and radially aligned with the outer face of the annular radiator, and an air propeller disposed within said central space of the radiator for forcing air drawn through said central opening and air returned by said casing radially outward through said annular radiator.

2. A heat exchanger comprising an annular radiator surrounding a central space and made up of a plurality of straight radiator sections arranged end to end in the form of a regular polygon, a casing surrounding and spaced from the annular radiator and having central openings adjacent said central space and side openings radially aligned with and adjacent a part of the outer face of the annular radiator, said casing acting to return a part of the air propelled outward through the annular radiator to said central space, and an air propeller disposed within said central space of the radiator for forcing air drawn in through said central openings and air returned by said casing radially outward through said annular radiator.

3. A heat exchanger comprising an annular radiator surrounding a central space, a casing surrounding and spaced from the annular radiator and having central openings adjacent the central space of the annular radiator and side openings adjacent and radially aligned with the outer face of the annular radiator, said casing acting to return a part of the air propelled outward through the annular radiator to said central space adjacent said central opening, and two spaced propellers of opposite pitch rotatably mounted coaxially within said central space of the radiator and respectively disposed adjacent said central casing openings for forcing air drawn in through said central openings and air returned by said casing radially outward through said annular radiator.

4. A heat exchanger comprising an annular radiator surrounding a central space, a casing surrounding and spaced from the annular radiator and having central openings adjacent the central space of the annular radiator and side openings adjacent and radially aligned with the outer face of the annular radiator, said casing acting to return a part of the air propelled outward through the annular radiator to said central space adjacent said central openings, two spaced propellers of opposite pitch rotatably mounted coaxially within said central space of the radiator and respectively disposed adjacent said central casing openings for forcing air drawn in through said central openings and air returned by said casing radially outward through said annular radiator, and an air bafile disposed in said central space between said propellers for directing air from said propellers radially outward from said central space.

5. A heat exchanger comprising an annular radiator surrounding a central space, a casing surrounding and spaced from said radiator and having central openings adjacent the ends of said central space and side openings adjacent and radially aligned with the outer face of said annular radiator, said casing acting to return a part of the air propelled radially outward through said annular radiator to said central space adjacent said central openings, at least one air propeller disposed within said central space of said radiator for forcing air drawn in through said central openings and air returned by said casing radially outward through said annular radiator, and means for adjustably altering the area of said casing side openings.

6. A heat exchanger comprising an annular radiator surrounding a central space, a casing surrounding and spaced from said radiator and having central openings adjacent the ends of said central space and side openings adjacent and 6 radially aligned with the outer face of said annular radiator, said casing acting to return a part of the air propelled radially outward through said annular radiator to said central space adjacent said central openings, at least one air propeller disposed within said central space of said radiator for forcing air drawn in through said central openings and air returned by said casing radially outward through said annular radiator, and sleeves slidably disposed on said casing and adjustably movable over said casing side openings to adjustably alter the area thereof.

LUDWIG R. HUBER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,368,392 Young Jan. 30, 1945 2,476,543 Geissler et a1. July 19, 1949 FOREIGN PATENTS Number Country Date 520,651 Great Britain Apr. 30, 1940 

